When the trailer for Doctor Who season nine debuted a few weeks back the biggest talking point was an appearance by Game Of Thrones’ Maisie Williams, uttering the apparently significant line to the Doctor, “What took you so long old man?”

Doctor Who’s internet fandom exploded. The implication seemed to be that she was someone the Doctor knew. so, who? His granddaughter, Susan, a Time Lord who travelled with him when we first met them in the very first episode back in 1963? The Rani, an evil female Time Lord? An earlier incarnation of River Song? Another incarnation of one-time companion Romana?

Yesterday, showrunner Steven Moffat blew all those theories out of the water… then back-pedalled slightly.

At the Television Critics Association summer press tour in Beverly Hills yesterday, Doctor Who’s executive producer said, “She is not playing a returning character, she’s a brand new character. She’s not someone from the Doctor’s past… unless I’m lying.”

Of course, he has lied before: about the fact that it was really the Doctor who was killed at the start of season six (by “The Impossible Astronaut”); about never using the Master. So deliberate brazen fibbing to disguise a surprise isn’t beyond Moffat. However his press release quote when Williams’s casting was announced earlier this year certainly doesn’t hint at any deeper connection: “It’s not possible to say too much about who or what she’s playing but she is going to challenge the Doctor in very unexpected ways. This time he might just be out of his depth, and we know Maisie is going to give him exactly the right sort of hell.”

Whatever the case, Moffat added at yesterday’s press tour that her role was still a meaty one. “It’s a significant role. We’re not throwing her away. We’re not getting the star value and doing nothing with it. It’s a great part and she’s terrific in it. But I would say it will develop in unexpected ways.” Which suggests that if we haven’t seen her before we may see her again.

“I think once you see what she’s up to in the show you’ll appreciate what a clever idea of [co-executive producer] Brian Minchin’s that was,” he added.

Jenna Coleman also confirmed that Clara will be a slightly changed character in the new season: “She’s no longer divided between Earth life and TARDIS life. There’s a sense of fearlessness, of reckless abandon. She can throw herself into adventures head first.”